1. Field of the Invention
This invention is in the general field of television testing methods and apparatus, it is more particularly directed to a method and apparatus for sweep testing in connection with cable television and the like. The invention is more directly related to a method and apparatus for the utilization of time division multiplexing between the test signal and the program signal in such manner as to eliminate interference between the program signal and the test signal in order that each may be displayed without interference. The invention utilizes a combination of means to generate the test signal, synchronization of test signal timing and transmission cooperative with the program signal, means to supress program material in the time position where the test signals will be applied; a means to synchronize detector and display, means to generate control and timing signals and apply them to test signal equipment, and a means to couple the test signal onto the network.
2. Description of the Prior Art
In the cable television industry it is known that there must be constant testing of signal strength and quality due to the nature of the distribution network wherein there may be numerous impairments due to bad tuning, bad connections, equipment failure, vandalism, nature elements, and the like.
Because of these problems the networks are monitored on a continuing basis. The methods used before the present invention included the insertion of a frequency sweeping test signal at some point in the input of a major distribution trunk and observation of its detected wave form at various points along the distribution network. The detector means and display amount to a spectrum analyzer. At the present time the testing in this manner creates certain interference with program signals which is most undesirable, or the test display will be cluttered with the regular program display, reducing its effectiveness. Additionally, the test display will be less than fully effective since it cannot normally be interjected at full strength because of program and test signal mutual interference.
For the first time the present method and apparatus involves the utilization of time division multiplexing between the test signal and the program signal applied to the distribution network in such manner that the program signal is not affected by the test signal and vice versa.